Power programming system for a centerless grinder

ABSTRACT

A power programming system for a centerless grinder which sets a reference input power consumption dependent upon the size of stock being ground, the depth of cut and the nature of the material and which measures or senses the power consumed and controls the rate of feed of the workpiece to have the power consumption equal the input value. The rate of feed of the workpiece may be varied within limits by varying the speed of the feeding mechanism for the workpiece and within greater limits by varying the helix angle of components of the feeding mechanism.

United States Patent [191 Schaller POWER PROGRAMMING SYSTEM FOR A CENTERLESS GRINDER [75] Inventor: Robert L. Schaller, Camillus, N.Y.

(73] Assignee: Sundstrand Syracuse, Inc.,

Syracuse, N.Y.

[22] Filed: May 4, 1973 [21] Appl. N0.; 357,390

[52] 11.8. C1. 51/103 TF, 51/165.92 [51] Int. Cl B241) 3/18 [58] Field of Search 51/103 R, 103 TF, 135,

[56] References Cited UNITED STATES PATENTS 1,996,467 4/1935 Ernst 51/l65.77 2,648,176 8/1953 Zimmerman... 51/135 2,807,917 10/1957 Fuller 51/103 TF 2,818,688 l/1953 Swedmark... 51/103 WH 2,961,808 11/1960 Dunigan 51/l65.92

P o vvE/e SEA/50R ACTUHTO 70 Jan. 14, 1975 3,503,156 3/1970 Schaller ..51/l39 3,589,077 6/1971 Lenning 3,654,737 4/1972 Schmidt ..5l/l65.92

Primary Examiner-Harold D. Whitehead Attorney, Agent, or Firm-Wegn er, Stellman, McCord, Wiles & Wood [57] ABSTRACT A power programming system for a centerless grinder which sets a reference input power consumption dependent upon the size 7 of stock being ground, the depth of cut and the nature of the material and which measures or senses the power consumed and controls the rate of feed of the workpiece to have the power consumption equal the input value. The rate of feed of the workpiece may be varied within limits by varying the speed of the feeding mechanism for the workpiece and within greater limits by varying the helix angle of components of the feeding mechanism.

11 Claims, 4 Drawing Figures ISPL Y D A 104 PATENTEDJAH 141975 v WEEK 18? 2 PATENTED JAN 1 41975 SHEET 2 BF 2 POWER PROGRAMMING SYSTEM FOR A CENTERLESS GRINDER BACKGROUND OF THE INVENTION This invention pertains to power programming systems for centerless grinders.

One type of centerless grinder which may have a power programming system associated therewith is shown in Schaller US. Pat. No. 3,503,156. This patent includes structure for feeding a workpiece relative to one or more grinding elements and with the rate of rotation and the helix angle of the feed elements being variable.

The control of inclination of input and outlet feed wheels for feeding a workpiece relative to a grinder is shown generally in Swedmark US. Pat. No. 2,818,688.

The Ernst U.S. PaLNo. 1,996,467 discloses a grinding machine with a workpiece supported on a travelling table. An electrical control system detects power consumption by a motor operating the machine and with changes in power consumption varying the rate of travel of the table which supports the workpiece. There is no disclosure in this-patent of any selective setting of the power consumption rate nor of such control in a centerless grinding system.

SUMMARY At the present time, an operator can set up a centerless grinder and it is desirable to take the production capability of such a machine away from an operator and provide for automatic control. The horsepower now available in centerless grinders exceeds the amount of horsepower that can be utilized in certain instances. For example, a centerless grinder, as commercially available, can be used through a very broad range of workpiece diameters, such as bar diameters, from a diameter of approximately inch to as large as 7 or 8 inches. Correspondingly, the through-feed rates may vary from 3 fpm to 200 fpm. If the centerless grinder has atwo hundred horsepower capability, such horsepower is not usable with a small diameter workpiece because of such bars not being perfectly straight and tending to whip if the through-feed rate is not restricted. Additionally, the grindability is a variable, since differing materials, or the same material with different hardness, require different horsepower. The grinding of stainless steel bars requires more horsepower than that required for low carbon steel such as 1,020 low carbon steel. The power programming system predetermines the horsepower that can be utilized on various diameter bars with various depth of cuts and grindability ratios. This establishes a value of desired power consumption. The power consumed by the motor for the grinding element is sensed and any variation therebetween is used to modify the through-feed rate of a workpiece to bring the consumed power into match with the set desired power consumption. This variation in the through-feed rate may be accomplished by varying the speed of'rotation of the regulating wheel as well as the input and outlet feed wheels for the workpiece, or the helix angles thereof which are set to provide for feed of the workpiece resulting from rotation of the wheels.

A primary feature of the invention is in a power programming system for a centerless grinder having a grinding element and means for feeding a workpiece relative to the grinding element, wherein variable means are provided for setting the desired power consumption in grinding, dependent upon the size of the workpiece, the depth of cut, and the grindability thereof along with means for sensing the actual power consumed in grinding and with means for controlling the feed of the workpiece to have the workpiece travel at a rate whereby the consumed power is at the set rate.

The centerless grinder includes a regulating wheel coacting with the grinding element as well as input and outlet feed wheels, with all of said wheels being set at a helix angle whereby their rotation results in feeding of a workpiece and with control of the feed rate of the workpiece being provided by either varying the rate of rotation of said wheels or the helix angle thereof, or both.

An object of the invention is to provide a power programming system for a centerless grinder having a grinding element and a coacting regulating wheel, drive means for the grinding element including a motor, input feed wheels for feeding a workpiece toward the grinding element, outlet feed wheels for feeding a workpiece from the grinding element, a series of motors for said wheels, means for operating said series of motors, comprising, settable means for setting the desired power to be utilized by said motor in grinding a workpiece, means for sensing the power consumed by the motor for the grinding element, and means for detecting a difference between the consumed power and desired power utilization and for modifying the operating means for the series of motors to feed the workpiece at a rate to have the consumed power match the desired power utilization.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic view of the power programming system for a centerless grinder;

FIG. 2 is a fragmentary plan view of a centerless grinder;

FIG. 3 is a fragmentary elevational view taken generally along the line 33 in FIG. 2; and

FIG. 4 is a side elevational view of the structure at a grinding station of a centerless grinder and taken generally along the line 4--4 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT A schematic view of the power programming system is shown in FIG. 1, with the structure of a centerless grinder shown more particularly in FIGS. 2-4.

A centerless grinder which may incorporate the power programming system has three major components, as shown generally in FIG. 2. There is an input feed section for the workpiece, indicated generally at 10, one or more grinding stations, with one station being indicated generally at 11, and an outlet feed section for a workpiece, indicated generally at 12. The structure of a centerless grinder, shown in FIGS. 2-4, is of the type disclosed in the Slchaller US. Pat. No. 3,503,156 and the disclosure of said patent is incorporated herein by reference.

The input feed section includes opposed pairs of feed wheels 15 and 16 with the mounting of each being of the same construction and the mounting for one of the feed wheels 16 being shown in FIG 3. The main frame of the centerless grinder input or outlet feed section includes a plate 20 mounting a base member 21 which mounts a slidable member 22 having an upstanding flange 23 with an apertured end receiving a trunnion 24 which supports the feed wheel 16 by means of a yoke member 25 rotatably mounting a shaft 26 carrying the feed wheel 16. With the mounting provided by the slidable member 22, the spacing between the feed wheels 15 and 16 may be varied. The shaft 26 of each of the feed wheels is driven from a drive shaft 27 with suitable universal joint connections and with an additional drive shaft 28 driving the feed wheels 15. A motor 30 connects to the drive shaft 27, with a connecting chain 31 driving a jack shaft which connects to the drive shaft 28. In order for the feed wheels 15 and 16 to feed a workpiece, they are set at a helix angle whereby rotation thereof imparts linear movement to a workpiece. This helix angle is set by a rod 35 connected to each of the yoke members 25 by a swivel connection and with the rods 35 being connected to linear motors 36, such as hydraulic cylinders, for linear movement and resulting establishment of helix angles for the wheels 15 and 16.

The outlet feed section for a workpiece includes opposed pairs of feed wheels and 41 which are mounted in the same manner as the feed wheels 15 and 16 and as shown in FIG. 3. Rotation thereof is through a pair of drive shafts 42 and 43 driven by a motor 44 in the same manner as the motor 30 drive the drive shafts 27 and 28. The helix angles thereof are set by linear motors 45 and 46 in the same manner as described in connection'with the linear motors 36.

A typical structure at the grinding station is shown in FIGS. 2 and 4 wherein a grinding element, in the form of a wheel 50, is supported by a mounting 51 and driven through a belt 52 from a motor 53. Alternatively, the grinding element may be an endless belt supported by a back-up member, rather than the grinding wheel shown. A workpiece W is shown in position (FIG. 1) against the grinding element and is supported by a work-engaging blade 55 mounted in a conventional manner for movement in a frame 56. A regulating wheel 57 is mounted on a support 58 for angular movement relative to a column 59 and with the column being on a slide 60 which is adjustable relative to a base 61. The regulating wheel 57 is driven through a gear box by a motor 62 and with the supporting mounting for the regulating wheel 57 being tiltable by power from a motor 63 in order to adjust the helix angle of the regulating wheel.

The foregoing structure is shown schematically in FIG. 1. The motors 30 and 44 for driving the input and outlet feed wheels as well as the motor 62 for driving the regulating wheel may be hydraulic motors as part of a hydrostatic transmission with the hydraulic power source being indicated at 70. A pair of hydraulic lines 71 and 72 connect the power source with the motor 30. A pair of hydraulic lines 73 and 74 connect the power source 70 with the motor 44. A pair of hydraulic lines 75 and 76 connect the power source with the motor 62. Hydrostatic transmissions of this type are known and include an actuator 77 which may vary the output of the hydrostatic power source 70 to resultingly vary the speed of operation of the motors 30, 44 and 62 and the wheels driven thereby.

An input computer unit 80 has dial-in units 81, 82, and 83 for setting into the unit the diameter of the workpiece W, the grindability ratio thereof, and the desired depth of cut, respectively. This unit, in a known manner, provides an analog output signal which is an indication of the desired power consumption to be utilized in grinding the workpiece W, taking into account the above variables. The motor 53 for driving the grinding element 50 is shown as an electric motor, with a three line supply having lines 84, 85, and 86, and with a power sensor 87 having a sensing coil 88 around the line 86 to sense the actual power consumed by the motor 53 in operating the grinding element 50.

The power sensor 87 emits an analog signal which is summed with the analog signal from the input computer unit 80 by the summing unit 89 to produce an error signal which is applied via an amplifier 90 to cause the actuator 77 to adjust the hydrostatic power source 70 in one direction or the other to either increase or decrease the speed of the various wheels engaging the workpiece to obtain a match between the desired power consumption and the actual power consumed.

A secondary loop provides for control of the helix angle of the feed wheels 15 and 16 of the input section, the feed wheels 40 and 41 of the outlet section and the regulating wheel 57. The secondary loop includes a line connected to the outlet side of the summing unit 89 and inputting to a high limit comparator 101 and a low limit comparator 102, each of which has an adjustable setting to determine a high limit and a low limit respectively for the value of horsepower error. A signal derived from either of the comparators l0] and 102 is supplied to a helix angle up/down counter 103 with an output to a numeric read-out display unit 104 and with a digital to analog converter 105 converting an output from the counter 103 to an analog value which passes through an amplifier 106 and is applied to the motors 36, 45, 46 and 63 which adjust the helix angle of the various wheels in engagement with the workpiece to vary the through-feed rate of the workpiece W. The helix angle control is disclosed as based on minimum and maximum values of horsepower error. If the error becomes very negative, indicating a low load on the motor 53 for the grinding element, the low limit is exceeded as determined by comparator 102 which emits the signal to adjust the helix angle actuating motors. Conversely if the error becomes very positive, indicating high load on the motor 53, the high limit is exceeded as determined by comparator 101 and the helix angle of the wheels is changed in the opposite direction until the error is below the high limit.

The power programming system through the setting of a desired power consumption in input computer unit 80 sets a predetermined speed for the input and outlet feed wheels and the regulating wheel 57 and with the helix angle of these wheels being at some predetermined value. A workpiece W is then started through the system. In order to avoid premature sensing of the consumed power a probe 110 is interlocked with the power sensor 87 through a line 111. This probe detects the presence of a workpiece near the exit end of the grinding element 50. When the presence of a' workpiece is sensed; the power sensor 87 then determines the power consumed, with the summing unit 89 comparing the analog output from the power sensor 87 with the set rate of desired power consumption from unit 80 to operate the control as previously described.

All of the wheels for feeding of a workpiece have a trimming (speed) control (not shown) to provide for synchronization therebetween and compensate for wheel wear.

I claim:

1. A power programming system for a centerless grinder having a grinding element, means for feeding a workpiece relative to the grinding element at a selected rate of speed within a variable range of speeds including a regulating wheel and a variable speed drive unit, drive means for the grinding element including a motor, variable means for setting the desired power con sumption, means for sensing the power consumption of said motor, and means for continuously comparing the desired power consumption and the actual power consumption and controlling said variable speed drive unit of the workpiece feeding means to have the workpiece travel at a rate to cause the motor to consume power at the set rate during the entire grinding operation.

2. A power programming system as defined in claim 1 wherein the variable means for setting desired power consumption has inputs for grindability, workpiece diameter and depth of cut.

3. A power programming system as defined in claim 1 wherein said workpiece feeding means includes input feed wheels and outlet feed wheels which are disposed at a helix angle similarly to the regulating wheel in order to feed a workpiece by rotation thereof, and means for varying the helix angles of said wheels to have said consumed power equal said desired power consumption.

4. A power programming system as defined in claim 1 wherein said power sensing means is interlocked with a workpiece sensing probe at the grinding element whereby the power is not sensed until a workpiece is being ground by the grinding element.

5. A power programming system as defined in claim 1 wherein said workpiece feeding means includes input feed wheels and outlet feed wheels which are disposed at a helix angle in order to feeda workiece by rotation thereof, and said variable speed drive unit driving all of said wheels.

6. A power programming system as defined in claim 5 wherein the means for controlling the workpiece feeding means includes means to vary the helix angle of said wheels.

7. A power programming system for a centerless grinder having a grinding element and a coacting regulating wheel, drive means for the grinding element including a motor, input feed wheels for feeding a workpiece toward the grinding element, outlet feed wheels for feeding a workpiece from the grinding element. a series of motors for said wheels, variable speed drive means for operating said series of motors, settable means for setting the desired power to be utilized by said motor in grinding a workpiece, means for sensing the power consumed by said motor for the grinding element, and means for continuously detecting a difference between the consumed power and desired power utilization and for continuously modifying the operating means for the series of motors to feed the workpiece at a rate to have consumed power match the desired power utilization.

8. A power programming system as defined in claim 7 wherein said means for operating said series of motors includes a variable master power source connected to each of said series of motors.

9. A power programming system as defined in claim 8 wherein said wheels are all disposed at a helix angle whereby rotation of the wheels feeds a workpiece, and said series of motors adjusting the helix angle of said wheels.

10. A power programming system as defined in claim 7 wherein said settable means for setting the desired power includes inputs for grindability and diameter of a workpiece and desired depth of cut.

11. A power programming system as defined in claim 10 wherein said power sensing means is interlocked with a workpiece sensing probe at the grinding element whereby the power is not sensed until a workpiece is being ground by the grinding element.

l =l l l =l 

1. A power programming system for a centerless grinder having a grinding element, means for feeding a workpiece relative to the grinding element at a selected rate of speed within a variable range of speeds including a regulating wheel and a variable speed drive unit, drive means for the grinding element including a motor, variable means for setting the desired power consumption, means for sensing the power consumption of said motor, and means for continuously comparing the desired power consumption and the actual power consumption and controlling said variable speed drive unit of the workpiece feeding means to have the workpiece travel at a rate to cause the motor to consume power at the set rate during the entire grinding operation.
 2. A power programming system as defined in claim 1 wherein the variable means for setting desired power consumption has inputs for grindability, workpiece diameter and depth of cut.
 3. A power programming system as defined in claim 1 wherein said workpiece feeding means includes input feed wheels and outlet feed wheels which are disposed at a helix angle similarly to the regulating wheel in order to feed a workpiece by rotation thereof, and means for varying the helix angles of said wheels to have said consumed power equal said desired power consumption.
 4. A power programminG system as defined in claim 1 wherein said power sensing means is interlocked with a workpiece sensing probe at the grinding element whereby the power is not sensed until a workpiece is being ground by the grinding element.
 5. A power programming system as defined in claim 1 wherein said workpiece feeding means includes input feed wheels and outlet feed wheels which are disposed at a helix angle in order to feed a workiece by rotation thereof, and said variable speed drive unit driving all of said wheels.
 6. A power programming system as defined in claim 5 wherein the means for controlling the workpiece feeding means includes means to vary the helix angle of said wheels.
 7. A power programming system for a centerless grinder having a grinding element and a coacting regulating wheel, drive means for the grinding element including a motor, input feed wheels for feeding a workpiece toward the grinding element, outlet feed wheels for feeding a workpiece from the grinding element, a series of motors for said wheels, variable speed drive means for operating said series of motors, settable means for setting the desired power to be utilized by said motor in grinding a workpiece, means for sensing the power consumed by said motor for the grinding element, and means for continuously detecting a difference between the consumed power and desired power utilization and for continuously modifying the operating means for the series of motors to feed the workpiece at a rate to have consumed power match the desired power utilization.
 8. A power programming system as defined in claim 7 wherein said means for operating said series of motors includes a variable master power source connected to each of said series of motors.
 9. A power programming system as defined in claim 8 wherein said wheels are all disposed at a helix angle whereby rotation of the wheels feeds a workpiece, and said series of motors adjusting the helix angle of said wheels.
 10. A power programming system as defined in claim 7 wherein said settable means for setting the desired power includes inputs for grindability and diameter of a workpiece and desired depth of cut.
 11. A power programming system as defined in claim 10 wherein said power sensing means is interlocked with a workpiece sensing probe at the grinding element whereby the power is not sensed until a workpiece is being ground by the grinding element. 